Performance of an integrated circuit, such as an image sensor, can be dependent on the temperature. For example, dark current inside an image sensor is highly temperature dependent. The dark current will increase with an increase of temperature and higher dark current degrades the performance of the image sensor. Higher dark current impacts the dynamic range of the image sensor, the dark reference level, and can cause various defects in captured images. If the temperature becomes too high, the sensor is susceptible to permanent damage.
One conventional technique for measuring the temperature of an image sensor is to mount a thermal couple on the package of the image sensor, either at the front side or at the back side of the package, depending on how the sensor is mounted on the circuit board. The thermal couple can occupy a lot of space and make a camera or other image capture device bulky. Also, over time, the epoxy used to affix the thermal couple to the package can age and become loose. And the temperature typically cannot be measured until the loose epoxy is repaired.